Protective device for commutator-type alternating-current motors.



B. G. IIIAMME.

UTATOR TYPE ALTEBNATING CURRENT MOTORS. APPLICATION FILED JUNB30,1904.

. v PROTECTIVE nnvwn ron comm Patented June -1, 1909.

BENJAMIN G. LAMME, OF

PITTSBURG, PENNSYLVANIA,

ASSIGNOR TO WESTINGHOUSE- ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

PROTECTIVE DEVICE FOR GOMMUTATOR-TYPE ALTERNATING-GURR ENT MOTORS.

Specification of Letters Patent.

Patented June 1,1909.

Application filed June so, 1904. Serial No. 214,822.

. To all whom it may concern:

, Current Motors,

Be it known that I, BENJAMIN a citizen of the United States, and a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have new and useful Improvement in Protective Devices for Commutator-Type Alternating- G. LAMME,

specification.

My invention relates to alternating currentmotors in which current is supplied to the windings of both members and in which the current to the rot'ative member or armature is supplied through a commutator substantially 1n the manner utilized in those operated by direct currents, and more especially my invention relates to motors of this character in which the field ma nets are shunt wound or separately excite instead of being connected in series with the armature windings. e

The object of my invention is to provide a protecting means whereb circuit will be automatica ly opened a predetermined length of time after interruption of the armature circuit is effected.

In motors of the character indicated, the coils of the armature which 'are short-circuited by the commutator brushes constitute secondaries to the field magnet winding, and since the latter is energized by alternating currents, secondar currents are generated in the former. s iich currents are not injurious so long as the armature is in motion, since the short circuit is transferred from coil to coil and the heat generated by the current in the short circuit 'is therefore dis tributed throughout the armature windings.

If the armature is topped, however, by in-- terrupting its circuit Without opening the field magnet circuit, the short circuit through the commutator brush is confined to a single coil or local portion of the armature winding, and if the short circuit is maintained for any considerable period, the heat generated may cause serious damage.

In the single figure of the accompanying drawing, I have illustrated diagrammaticoperation therefronr at substantially constant speed and protective means constructed to operate in accordance with my' invention.

As here illustrated, the field ma'gnet winding 1 of the constant speed motor 2 is coninvented a of which thefollowing is a the field magnet closed, the lifting serve to retain t mented by a spring,

armature and field magnet circuits are closed,.the'operation will be satisfactory. If, however, the armature circuit should be opened, either accidentally. or"

otherwise, whereby the armature. would come to rest, serious dama cm the motor might result by reason 0 the conditions hereinbefore mentioned. In order to avoid such injury, I include in the circuit of the field magnet an automatic circuit breaker 5, which may be of any suitable, we'll-known construction. In the present instance, I

have indicated the breaker as locked closed position by-means of the toggle joint structure 6 and depending from the toggle joint locking device is a rod 7 having a lateral projection 8 at its lower end'in posi tion to be engaged by the core 9 of a solenoid 10, this solenoid being located in the armature circuit and the core being connected by means of a rod '11 to the piston 12 of a dashpot 13. I have also indicated a circuit breaker 14 in the armature circuit.

So long as the armature circuitremains action of the solenoid will e core in substantially the position indicated. If the armature circuit is opened, however, the core will descend by the action of gravit which may ice-suppleif desirechbut' the descending movement will beretarded by the dash-pot, so that if it is desired to manipulate any controlling or switching device in the armature circuit for the purpose of again closing that circuit or for any other-purpose,

the opening of the field magnet circuit will be sufiiciently delayed to permit of such operation. If, however, the armature circuit is not closed, the solenoid core will, at the end of a predetermined interval of time,

engage the projection 8 on the rod 7 and 'thus trip the circuit breaker 5, ally a supply circuit, a motor adapted for The specific form of protective apparatus here shown is merely indicative of any apparatus suitable for the purpose and is obviously susceptible of many modifications and variations within the scope of my invention.

I claim as my invention:

1. The combination with a constant speed,

commutator-type motor, of an interrupter for the field magnet circuit and means for actuating said interrupter to quickly open the said circuit a predetermined interval of time after the armature circuit is broken.

2. The combination with a commutatortype motor having armature and field magnet windings separately supplied with alter nating currents, of an interrupter in the field magnet circuit, a tripping device therefor that is retained in inactive relation by the armature current, and means for delaying; the, action of the tripping device until a predetermined interval of time has elapsed after the opening of the armature circuit.

3. The combination with two-phase alternating current circuit and a commutatortype motor havingits armature and field 'magnet windings connected to the respective hases of said circuit, of an interrupting de'vice'for the field magnet circuit and operating means therefor which is rendered inactive so long as the armature circuit is closed and which operates said device a pie determined interval of time after the armature circuit is opened.

4. The combination with an alternating I current c rcuit and a commutator-type motor i an interrupting device for the. field magnet circuit and a controlling n'ieans therefor which insures quick operatioit-of the inter-- 'rupting device apredetermined interval of time after the armature circuit is opened.

5. The combination with an alternating current circuit and a motor having its armature and field magnet windings separately supplied by said circuit, of a breaker for the field magnet'circuit and tripping mechanism for said breaker comprising a' coil in the armature circuit, an armature, a breakerreleasing member adapted to be actuated by ,said armature after a given amount of lost motion, and a dash-pot for said armature. 3 In testimony whereof, I have hereunto subscribed my name this 28th day of June,

- Y BENJ. G. LAMME.

Vitnesses E. M. STEUART, BIRNEY HINES. 

